Outstanding white sharp truscottite crystals with a good contrast with the matrix and from Bras de Cilaos (Cirque de Cilaos, Piton des Neiges, Reunion). Analyzed specimen. — Photo: David Hospital · CC BY-SA 4.0
Truscottite
Truscottite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₁₄Si₂₄O₅₈(OH)₈·2H₂O.
It crystallizes in the hexagonal crystal system. It is a member of the Gyrolite structural group.
Key properties: Mohs hardness 3.5; specific gravity 2.47–2.48; Pearly on the cleavage luster; optically uniaxial.
IMA symbol Tst, grandfathered status — known before the IMA’s founding, named in 1914.
Found in epithermal gold-silver quartz veins cutting altered pyroclastics (Toi mine, Japan).
It is found associated with Quartz, adularia, rhodochrosite (Toi mine, Japan).
The name refers to Professor Samuel John Truscott (1870{?), English mining geologist and formerly Manager of the Lebong Donok mine, Sumatra.